As the elderly population increases, it is projected to increase the number of patients with degenerative diseases involving dementia including Alzheimer's disease. Since these diseases progress with increasing age to cause the patients and life environments around them to change, it is important to diagnose in the early stages.
Such degenerative diseases involving dementia are mainly diagnosed by diagnostic procedures based on clinical findings such as doctor's questions as typified by Mini Mental Status Examination (hereinafter referred to as “MMSE”). However, the diagnostic procedures based on the clinical findings have low sensitivities in the early stages of symptoms, and the diagnostic outcomes by the diagnostic procedures tend to be affected by cognitive functions innately owned by individuals. Because of such background in the diagnosis for the degenerative diseases, a method is expected which can detect pathologic changes more objectively.
On the one hand, recent researches have revealed that the occurrence of the degenerative diseases involving dementia decreases a glucose metabolism rate partly (for example, see Nonpatent Document 1). Nonpatent Document 2 described below discloses a method of detecting degenerative diseases utilizing this. This method involves comparison of a PET image by administration of 2-[18F]-fluoro-2-deoxy-D-glucose (hereinafter referred to as “FDG”) as a tracer for glucose metabolism with that of a normal group to calculate t values of individual pixels, thereby distinguishing a patient with Alzheimer's disease from normals.    [Nonpatent Document 1] Kazunari Ishii, “Clinical application of positron emission tomography for diagnosis of dementia”, Annals. of Nuclear Medicine, 2002, 16(8), p. 515-525    [Nonpatent Document 2] K. Herholz et al., “Discrimination between Alzheimer dementia and controls by automated analysis of multicenter FDG PET”, NeuroImage, 2002, 17, p. 302-316